data NonEmptyList a = Element a (NonEmptyList a) | LastElement a deriving Show

length:: NonEmptyList a -> Int
length (LastElement _) = 1
length (Element _ list) = 1 + Main.length list

map:: (a->b)->NonEmptyList a->NonEmptyList b
map f (LastElement a) = LastElement (f a)
map f (Element a list) = Element (f a) (Main.map f list)

foldl:: (a->a->a)->a->NonEmptyList a->a
foldl f acc (LastElement a) = f acc a
foldl f acc (Element a list) = Main.foldl f (f acc a) list

foldr:: (a->a->a)->a->NonEmptyList a->a
foldr f acc (LastElement a) = f acc a
foldr f acc (Element a list) = f a (Main.foldr f acc list)

infixr 5 .++
(.++):: NonEmptyList a -> NonEmptyList a -> NonEmptyList a
(LastElement first) .++ second = Element first second
(Element first firstList) .++ other = Element first (firstList .++ other)

elem:: Eq a=>a->NonEmptyList a->Bool
elem a (LastElement b) = (a==b)
elem a (Element head list) = (a==head) || Main.elem a list